The separation of a flowing medium mixture has very diverse applications. For purposes of the present disclosure, medium mixture means a mixture of at least one liquid or a gas which can be mixed with solid material parts, such as a powder or an aerosol. Examples are a gas/gas mixture, a gas/liquid mixture, a liquid/liquid mixture, a gas/solid mixture, a liquid/solid mixture, or any of the mixtures provided with one or more additional fractions. The separation of a flowing medium mixture is, for instance, known from various applications of liquid cleaning, (flue) gas cleaning and powder separation. Separation of fractions with a great difference in particle size and/or a great difference in mass density is relatively simple. Large-scale use is made of processes such as filtration and screening. In the separation of fractions with a smaller difference in mass density, chemical separating techniques and/or separating techniques such as sedimentation and centrifugation are used. A relatively simple and, therefore, inexpensive technology, with which large volumes can be separated in line, makes use of the differences in mass density of the fractions for separating by applying a centripetal force to the mixture by means of rotating the mixture in, for instance, a centrifuge or a cyclone. A relatively simple separating device comprising a stationary housing in which a vortex, i.e., a rotating mixture, can be generated is, for instance, described in International Patent Application Nos. 97/05956 and 97/28903. These devices are also referred to as “hydrocyclones” and are particularly suitable for liquid/liquid separation. It is noted that the fractions obtained after separation can still have (or be contaminated with) a part of the other fraction even after separation, although the fractions both have a composition clearly differing from the composition of the original mixture.
As a result of the rotation of the mixture in a stationary housing of the cyclone, a lighter fraction will at least substantially migrate to the inner side of the vortex and a heavier fraction will migrate to the outer side of the vortex. The heavier fraction and the lighter fraction are discharged at spaced-apart positions from the cyclone.
French Patent Application No. 2134520 describes a cyclone comprising a first feed part connecting radially to the separating space. The cyclone is also provided with a throughfeed part which allows passage of the mixture in a lateral direction and to which a guide with curved guide elements is connected, whereby a radial flow direction is obtained. Once the mixture has been set into rotating movement, the mixture is carried through a separator tube. Use of this construction will at best result in a mediocre separating result.